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(No Model.)

J. B. LONG.-

HOT AIR FURNACE.

Patented May 14,

N. PETERS. PhnhvLithagnplver. Waihingiun. c.

UNITED STATES JAMES B. LONG, OF ROCHESTER, NEW YORK, ASSIGNOR TO REBECCA LONG, OF SAME PLACE.

PATENT OFFICE.

HOT-AIR FURNACE.

SPECIFICATION forming part of Letters Patent No. 403,278, dated May 14, 1889.

Application filed October 1, 1887.

To all whom it may concern..-

Be it known that I, JAMES B. LONG, of Rochester, in the county of Monroe and State of New York, have invented a certain new and useful Improvement in Hot-Air Furnaces; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the drawings accompanying this application.

My improvement relates to that class of hot-air furnaces in which an indirect draft is produced by means of pipes that pass up and down at the side of the dome and a crosspipe connects them at the top.

The invention consists in the combination, with the pipes and with a horizontal flue in the base, of an air-trunk at the bottom, which passes through the cold-air chamber and opens directly under the flue, so that the cold air that enters from the outside will be brought into contact with the hot-air flue on the under side, and will become partially heated before passing up through the furnace, as hereinafter described.

In the drawings, Figure 1 is a central vertical cross-section of the furnace. Fig. 2 is a similar section at right angles to Fig. 1.

A indicates the base of the furnace, which rests on brick-work B, so as to form a coldair chamber, a, beneath. O is the ash-pit. D is the fire-pot, and E the dome, all of ordinary construction. F is the exterior casing, which may be made either of galvanized iron or brickwork.

My improvement is as follows:

G is a hollow troug shaped flue on the under side of the base and in the cold-air chamber a. This flue forms a passage from one side of the furnace to the other at right angles to the ash-pit.

H and H are two vertical pipes extending from the flue G upward on opposite sides and connected at the top by a horizontal pipe, H which extends over the dome and is connected therewith by a throat, b. 011 one side this horizontal pipe extends outward, as shown at H and forms the exit-pipe, and on the other it is provided with a removable cap to permit access for cleaning the same. The pipe H has a damper or valve, c, between the exit- Serial No. 251,220- (ll'o mocleh) H lies within the'casing of the furnace andthe pipe H outside of it, as shown in Fig. 1. By this means the products of combustion that escape from the dome and first pass down the pipe H radiate heat directly into the hotair chambers of the furnace, and then when they become cold in their further passage they pass up outside, by which means very little heat is lost from the furnace.

I is a cold-air trunk or passage extending through the brick-work into the cold air chamber or space a. In common furnaces of this kind this air-trunk simply opens into the chamber, and the cold air at once rises at the sides and without coming in intimate contact with the bottom of the hot-air flue. It is the special object of my invention to bring it in contact with the bottom of the flue, so that it cannot escape upward till it has spread over the whole bottom and extracted the heat from the flue. To accomplish this result, the airtrunk I'is carried under the flue and is provided with closed sides that hold it in contact with the bottom till the proper point is reached, when the air escapes through the open end. By this means the cold air that enters at the bottom becomes heated to a much higher degree before it escapes upward than it does in common furnaces. This feature, in combination with the downward -flue arrangement, constitutes the essential feature of my invention.

K is a long pipe of smaller diameter than pipe H, which'long pipe extends vertically downward through pipe H, also through the top of pipe H and the bottom of flue G. By this means a portion of the cold air passes from the cold air chamber or space a up through pipe K, and escapes into the top of the furnace-space and becomes highly heated in its passage, owing to the great heat that passes down pipe II. This adds greatly to the heating capacity of the furnace.

It should be understood that the larger part of the air admitted through trunk I cends around trunk G and ash-pit G and in contact with the body of the furnace and with 5 the exterior of pipe II.

I am aware that cold air has been admitted to a base-chamber of a hot-air furnace, and thence directed by a fiue against the bottom of the ash-pit of the furnace, and that in fur- IO naces having indirect draft one or more of the downdraft-pipes have been placed in air-fines, and I do not claim such devices, but only the matters herein described and particularly pointed out.

In my construction a flue or trunk, 1, conveys air to a point immediately under a horizontal part, G, of the indirect conduit or flue for the products of combustion, which flue crosses the ash-pit in immediate contact therewith. By this arrangement the fresh i11- coming air is delivered immediately under the bottom of the flue at a point where the latter is protected from the air on its top by the ash-pit; and, further, the flue G extends entirely across the furnace and on one side beyond its casing, and by its connections rests upon the masonry and aids in supporting the fire-chamber; also, this extension of flue G beyond the casing affords means for connecting o therewith the flue II, which is located without the casing. The diving-flue H is within the casing, and while it is exposed to air externally, as heretofore practiced, it also has within it a cold-air pipe. By this arrange- 5 ment it is practicable to reduce the heat of the products of combustion below that of the upper part of the hot-air chamber, which is not possible where the indirect flue lies wholly in said chamber and is exposed externally to 40 the air therein.

I-Ieretofore an indirect flue has been extended down below and around the ash-pit and passed out through the furnace-casing at a higher level, and a conduit for fresh'air has 5 been arranged transversely to such flue,whe1eby the air was partially warmed and directed. against the ash-pit, as described in patent to Van Buren, No. 645,599, and such constructions are not of my invention; nor do I claim an air- 0 pipe located in a smoke-space or smoke-flue except when said smoke-flue is placed in the air-chamber of a furnace, whereby I expose the hot products in an annular current to walls separating it from air both interiorly and exteriorly and all within the furnacecasing.

Having described my invention, I do not claim simply and broadly a downward-flue arrangement in a furnace; nor do I claim, broadly, a cold-air trunk opening into the base of the furnace.

hat I claim as new, and desire to secure by Letters Patent, is

1. In a hot-air furnace, an air-chamber, a cold-air inlet, a combustion-chamber, a flue for products communicating with the combustion-chamber and extending downwardly, and having vertical and horizontal parts within the hot-air chamber, and the air-pipe located within the vertical part of said flue and communicating at its top and bottom with the air-chamber, whereby both the exterior and the interior of the current of escaping products are utilized to heat the air and the escaping products thoroughly cooled within the casing, and an updraft-pipe located outside the furnace, whereby said pipe and the interior of the horizontal part of the flue within the casing are made conveniently accessible, substantially as specified.

2. A hot-air furnace having a combustionchamber, an ash-pit, an indirect-draft flue including a downdrafbpipe located in the airspace and an updraft-pipe outside the easing, the two being conn eeted by a horizontal flue supporting the bottom of the ash-pit and supported by the masonry on which the furnace stands, said furnace having a direct flue connecting an upper horizontal part of the downdraft-pipe with the combustion-eha1nher, and also with the top of the exterior updraft flue or pipe, said part being at its opposite end extended through the furnace and provided with a cap, all as shown and described, whereby the exterior flue is made accessible, and whereby both horizontal flues may be easily cleaned, and the several parts so connected as to support each other, substantially as specified.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

J. 13. LONG. IVitnesses:

R. F. OSGOOD, JACOB SPAHN. 

